1. Field of the Invention
The present invention relates to a vitamin D.sub.3 based lactone, derivative which is useful as a pharmaceutical. More specifically, it relates to 1.alpha.,25-dihydroxy vitamin D.sub.3 based lactone derivatives useful as an accelerator of bone formation (i.e., an osteogenetic accelerator), a suppressant of tumor cell proliferation, a drug for treating hypercalcemia, or other pharmaceuticals, a process for production of the same, and an intermediate for the production thereof.
2. Description of the Related Art
The fact that the metabolites of vitamin D.sub.3 perform an extremely important function as substances controlling the metabolism of calcium and phosphates in the living body is now becoming widely recognized through numerous disclosures in patents and general references. Recently, further, an increase is being seen in clinical applications as drugs for treatment of various ailments, such as with the discovery of numerous substances having the ability to induce differentiation of tumorous bone marrow cells. Further, recently, a novel vitamin D.sub.3 active metabolite having an .alpha.-hydroxylactone ring at a steroid side chain has been discovered (Arch. Biochem. Biophys., 204, 339-391 (1980); FEBS LETTERS, 134, 207-211 (1981)). This compound is 1.alpha.,25-dihydroxy-vitamin D.sub.3 -26,23-lactone and is represented by the structure shown below: ##STR2##
This compound is reported to have actions such as an action of lowering the concentration of calcium in blood serum (Japanese Unexamined Patent Publication (Kokai) No. 58-118516), an action of suppressing the proliferation of tumorous cells (Japanese Unexamined Patent Publication (Kokai) No. 58-210011), an action of accelerating bone formation (Japanese Unexamined Patent Publication (Kokai) No. 60-185715), etc. and is expected to contribute much as a drug for treatment of various ailments.